BOSTON, Massachusetts (CNN) -- Colored by the terrorist attacks of 9/11, the four-day convention nominating John Kerry as the Democratic standard-bearer is unfolding under extraordinary security.

But the security has proved to be -- so far -- less of a burden than some had expected.

The thousands of delegates and journalists are moving smoothly in and out of the FleetCenter each day. There have been no evacuations, no massive traffic jams, and there are no evident disruptions to the proceedings because of any security scare. (Special Report map: The FleetCenter in Boston)

"It's going very well. We've had very few problems. Everything's running smoothly," said Zach Zubricki, a spokesman for the Joint Information Center, which is handling all security related questions at the convention.

There have been no convention-related arrests, Zubricki said, and any suspicious packages that have come to the attention of authorities have all been cleared.

Security is certainly a huge presence at this convention. A host of federal, state and local agencies -- including the FBI, Secret Service, Boston police and the Coast Guard --- have joined forces to manage the security, expected to cost at least $100 million for both political conventions this summer. (Military adds muscle to convention security)

Miles of roads, including part of one interstate, around the convention site have been closed, thousands of security personnel -- many armed -- patrol the site, helicopters hover overhead, checkpoints dot the perimeter of the FleetCenter, and police cars are stationed at the many hotels housing delegates.

Manholes have been welded shut, bomb-sniffing dogs are a familiar sight, and plans have been drafted for responses to possible chemical or biological attacks.

But many delegates said they don't feel overwhelmed or unnerved by the omnipresent security.

"I have no problem with the security. ... It's something that must be done for the times in which we live," said Beuenia Brown, a delegate from New York. "Safety first."

Some delegates who have been to previous conventions said they don't feel any more of a security presence than they have in pre-9/11 years.

"Going through security, I don't see it as any worse than years past," said Tim Kitchen, a delegate from Wisconsin, who has attended nine previous conventions.

Ann White, the wife of a delegate from Florida, admitted she was a little apprehensive about the convention before she arrived. She said she was worried about terrorism and anxious about security.

"It's not as much of a hassle as I thought it would be," she said.

The Boston Globe noted in a front-page headline this week that the security and road closures have proved to be less of an issue for commuters -- at least initially: "Easy does it on Day 1 for commuters."

The newspaper also reported, however, that some downtown businesses were feeling the squeeze from the security restrictions, seeing fewer customers.

The huge security presence has also frustrated some protesters, who have complained their voices have effectively been squelched. Protesters are confined to a fenced area outside the FleetCenter.

"We think the city of Boston has gone way overboard in the name of security," Leslie Cagan, a co-founder of United for Peace and Justice, said at a news conference this past weekend.

Mike Flathers, a vendor selling Kerry-Edwards souvenirs inside the FleetCenter, said there was little doubt security was strict.

While people moved about easily inside the center, he noted that various credentials restricted people to certain areas.

Laughing, he said he's tried to poke his head inside some hallways to get a better view of the proceedings.

"As far as security, it's tight," Flathers said. "They don't let you get anywhere you're not supposed to be -- and I've tried."